Size comparison analysis for 2D and 3D file

As shown below: 3D measurement size is 4.75 mm, and 2D is 5V1. What does 5V1 mean? Is not that the size is 5 mm? If the 2D representation is 5 mm, then difference of the 4.75 mm and 5 mm  is a lot. Is the drawings wrong? The next step is to confirm what this 5V1 means.